A Valve System of a Well Pipe Through an Hydrocarbon Containing Formation and a Method to Operate the Same

ABSTRACT

A method is described for the operation of a valve system for a production pipe (104) in a well (101) through a hydrocarbon containing formation with one or more valves (1a, 1b, 1c) that comprise one or more seats that are activated selectively by the use of a ball (5) of the same size, where the ball is set up to land on one or more ball seats (4a, b, c, . . . ) internally in the valve, where the seat (4a,b,c.) can be activated for landing of a ball (5a) either before driving into a well or by the passing of a previously released ball or other suitable object (5) of an adjusted diameter or shape. The method is characterised in that each applied valve (1a, 1b, 1c) comprises two separated casings 2 and 3, respectively, in the form of an inner casing (3) arranged inside an outer casing (2), where the inner casing (3) can be freely moved axially with regard to the outer casing (2) as the inner casing (3) comprises one or more ball seats (4), the one axially above the other, and which are activated to hold back a ball (5), successively in that the inner casing (3) is moved axially through the outer casing (2). A valve system for the same is also described.

The present invention relates to a method for the operation of a valvesystem as given in the introduction in claim 1, and also the valvesystem itself as given in the introduction in claim 7. In more detailthe invention relates to new features of a downhole ball valve that canbe activated.

The expression “oil well” refers, in general, to wells for extraction ofoil and/or gas. “Oil well” comprises a well in connection withexploration of new fields, new production wells that are being tested orwhich are being equipped for operation, production wells that areoperating and wells that are being set up, i.e. that is, that it isbeing made ready for production. The method and valve construction ofthe present invention are particularly suited for use in shale gaswells.

An oil well is normally comprised of several pipes inside each otherdown in a borehole, where the outer layer or layers are called casings,and an inner production pipe, and also control lines for carryingsignals for the control of the instrumentation in the well. The casingprotects the inner production pipe and holds the formations thatsurround the well in place so that they do not collapse into the well.They also protect against unwanted inflow of fluids from the surroundingformations.

At the completion and start-up of shale gas wells and oil wells or otheroil and gas wells, it is, in some cases, necessary to carry out acracking operation. This implies than one pumps a liquid down into thereservoir under high pressure so that the shale or the formation cracksopen. One does this to get a large surface down in the formation throughthe cracks so that the gas or the oil can flow easier in towards theproduction pipe.

When such a job is to be carried out, it is important to have goodcontrol of the pressure at the different zones in the well. At the sametime it is difficult to pump sufficiently large amounts of liquid downinto the well to reach the required pressure simply because of the largevolume of the whole well.

Therefore, it is common to divide the well into zones. Today, this isnormally done by applying (leading down) a rubber element that swells upin contact with hydrocarbons or water. These rubber elements are fittedon the outside of the production pipe that is led into the well at thereservoir. Then, the rubber elements swell up against the formation(well wall) and form a seal between the formation and the productionpipe. If one then inserts several such seals, one gets the well dividedinto a number of closed zones between these seals.

To get the well in production, there is, in addition, a valve normallyfitted that can be opened and closed between two such rubber elementsthat will make up a zone, this to give the oil/gas an opening into theproduction pipe so that it can flow and also to make an opening for thecracking liquid and flow in through this during the cracking job. Thedivision into zones results in that one only needs to pump a smalleramount of liquid down into the well. By using such rubber gasketsbetween each zone with valves in between, the cracking jobs becomesimplified and one does not need to pressurise the whole well but onlythe area between the two gaskets which make up a zone. This is carriedout in that the valve or valves are open in a zone between two gaskets,while the rest is closed. In this way one can selectively crack orproduce from the well and possibly close for the ingress of water thatarises in a different zone by closing the valves.

Another method to form zones is that one pumps cement (concrete) downthrough the production pipe and up on its outside so that the pipe isfastened to the formation by the cement. This cements is pumped downinto the production pipe from the surface and all the cement is forcedout of the production pipe and up along its outside in that one letsdown a cement arrow on the top of the cement which forces the cementdown in front of it when it is forced down into the production pipe bythe liquid pressure supplied from above. The production pipe is open atthe end and the cement will now flow out through this opening and upinto the annular space between the formation and the production pipe.This will leave the production pipe empty of cement internally andcemented securely to the formation.

The production pipe can also have a number of valves that can be openedand the division into zones will now be set up by the cement that sealsbetween each valve, as the area between the production pipe and theformation is filled by the cement.

When one then opens one of the valves, the pressure supplied from thesurface will be great enough to crack the cement in the immediatevicinity of the valve that is open but not great enough to crack thecement nearest the other valves. In this way one also gets the welldivided into zones.

The number of such zones and the number of valves in each zone varieswith the well conditions, but it is very common to have many zones fromfive up to 30 and each zone can readily have up to ten valves.

These valves can normally be opened/closed with a wireline interventiontool or they can be opened in that one drops a pellet or a ball downinto the tube in the well which then stops in a seat in the valve. Thepressure is then increased above the ball and a slide or casing ispushed down to open the valve. Normally this is achieved in that thevalve that is placed uppermost in the production pipe has a ball seatwith a large diameter and then reducing the diameter of the ball seatsuccessively down the well.

By first letting down a small ball in the pipe, one will then passthrough all the upper valves and get the ball landed on the seat in thevalve that lies at the bottom of the well which has a seat adjusted tothe diameter of the ball.

Thus, one can choose the correct valve according to the diameter of theball. This system creates restrictions in the well as one is dependenton ball seats with a large diameter at the top, which then getssuccessively smaller and smaller as one goes down the well.

It is the aim of the invention to provide a system where balls of thesame diameter can be used to open a number of valves in a well withoutthis creating restrictions in the well, as all the zones can be openedwith the large ball that is normally let down last to open the lastuppermost zone. This is achieved in that one sets up a constructionaccording to the invention which ensures that the upper valves count thenumber of balls that pass and first open when the right number of ballshas passed.

The method with different ball diameters that leads to a restrictionbeing set up in the well is unwanted considering the operations thatshall be carried out later in the well. These operations can be, forexample, well logging, placing of plugs and closing a sectionpermanently, or simply that the restrictions in the pipe represent athrottling of the production. For these reasons, the ball seats must bebored out from the pipe with the use of a costly operation with coiledpipes after the cracking job has been carried out so that the productionpipe in the well gets a uniform, large, inner diameter without therestrictions which the ball seats represent.

Review of Prior Art

Norwegian patent application NO 20100211 describes such a system withseveral ball sizes for each zone. It is based on two casings foractivation, an inner casing that contains a loose ball seat which isfastened in an outer casing with some shear pins. When the ball hits theseat, both casings will move down until a shear pin is broken and theball is released and moves down to the next valve where the operation isrepeated, to continue down the well so that all the zones open. Thissystem can indeed activate several valves by the use of the same balldiameter, but will leave all valves which the ball has passed, activatedand open. For that reason one cannot use the system to provide asolution where all the zones in a well can be controlled independentlywith one ball size. It is not desirable to open all the zones forcracking in one single operation because this will not lead to a goodresult. This system, like other systems, must use a procedure where onestarts with a small ball to open the bottom zone in the well, thereaftercontinuing to open the next zone with a somewhat larger ball. The systemcannot be reused for subsequent operations either, as it is based on ashear pin that allows the inner casing to loosen. This shear pin cannotbe replaced down in the well so the system can only be used once.

On the other hand, it can be preferred to have several valves in thesame zone by using the same ball diameter for the activation, where itwould be advantageous to use this solution in that each zone has its ownball diameter, i.e. the smallest at the bottom to increase the diameterupwards in the well.

Today, there are two solutions where one can use balls of the samediameter in all the zones.

One of them has an external indexing system which makes the casingrotate, also known as a “jay slot system” as described in the US patentno. 2013/248201. This lets the balls past until a wanted number ofrotations/indices on the casing has been reached. Typical for such asystem is that there is the highest number of rotation points on theupper casings and smallest on the lower.

The problem with this system is that one is dependent on a spring thatpushes the casing up again to the starting position after a completedrotation. This is so that the seat for the ball that has gone past shallbe activated again. These systems are also expensive and complicated tomanufacture and install, it is particularly expensive to cut out theexternal groove on the casing that shall generate the rotation.

The system is also very sensitive to contaminations and dirt in the wellliquid that comes into the groove and in the spring pocket and can leadto it locking completely. It is also difficult to zero the system, if anew cracking job or acid stimulating job shall be carried out, or simplythat one just wants to close the zone. The system will also cease tofunction if it is used in connection with the cemented production pipeor if the spring should break.

Another known system is one that is comprised of several cut grooves inthe pipe that the inner casing and the ball seats are indexed by, asshown in the British patent number GB-2.506.265. This system has a cutgroove for each position that the casing shall have and leads to acostly and complicated internal rotation to make, for example, 20-50such internal, exact cut-outs inside the valves. Another disadvantage isthat as it is described, all the grooves will be exposed to deposits andcoverings that can be lodged in the grooves and hinder the operation ofthe system.

The casing that carries out the actual activation is here a separatepart from the closing/opening casing, and the function is based on thatthe activation casing being moved a required number of times downwardsto finally land on the top of the closing/opening casing. This resultsin the opening casing being moved down to an open position with the helpof the hydraulic pressure that arises above the activation ball. It isimportant to note here that the activation casings with the ball seatshave the same outer diameter as the closing casing, and that they aretwo separate parts which cannot simply be moved to an open and closeposition as a unit.

Common to all these solutions is the disadvantage that they aredifficult to reset to the starting position after use. Therefore, theymust be regarded as system which can be used once only. Otherdisadvantages are that they require accurate control of the number ofballs that are dropped to get the indexing mechanism to go a completeturn or that the ball seat drops out of position in the last activation.The known systems are also exposed to deposits from preceding cementingjobs which means that they are, in general, not suited for use in wellswith a so-called cemented liner. When the production pipe “Liner” iscemented, cement will be pumped past all the valves and parts of thecement will then penetrate into the valves when it passes and hardeninside. This will make the operation of the valves impossible after thecementing job has been completed.

As mentioned, there are several systems that use balls of differentsizes. When we in this context talk about activating balls, it isimplied that it is not limited to round balls, but it can also beactivating cementing arrows of different kinds in the industry, or otherobjects that can be hydraulically pumped down in the well to land on aseat in the valve tool.

The systems that use balls of different sizes will not be relevant inthis connection as the aim here is to provide a tool that does not havethe disadvantages of several ball sizes as mentioned above.

With regard to prior art, reference is also made to WO 2010/127457,US-2011/030976 and US 2014/151054.

The Present Invention

The method according to the present invention is characterised in thateach applied valve comprises two separated casings in the form of aninner casing arranged inside an outer casing, where the inner casing canbe moved axially freely with regard to the outer casing, as the innercasing comprises one or more ball seats, the one axially above theother, and which are activated to hold back a ball, successively in thatthe inner casing is displaced axially through the outer casing.

The inner casing preferably pulls along the outer casing to an openposition when the ball lands on the last seat in the row in the innercasing so that it opens for a fluid connection between the inside of thepipe and the formation through aligned openings in the inner casing,outer casing and the valve, respectively.

Particularly preferred is that the last seat in the inner casing forms arestriction to prevent the ball being released when it lands on thislast seat.

According to a preferred embodiment, the last seat in an inner casingreleases the ball after opening of the outer casing that constitutes thevalve, for example, so that several valves are installed in the sameusing zone, where the bottom valve will then hold back the ball inaccordance with requirements and thereby make possible several openingsfor fluid flow out to and in from the same zone in the formation.

The well is preferably divided into zones in that the pipe, between eachset of valves, comprises gaskets that form a seal between the formationand the pipe. It is particularly preferred that the bottom valve set inthe production pipe comprises one single casing with one ball seat andalso openings uppermost around the pipe circumference to set up saidfluid flow to a first zone, a next valve set comprising two casings withrespective ball seats, where the uppermost casing comprises openingsuppermost around the pipe circumference to set up said fluid flow to asecond hydrocarbon-carrying zone, as each further set of valves in therow upward comprises one more casing than an underlying casing, as eachuppermost casing comprises said openings uppermost around the pipecircumference to set up said fluid flow between the production pipe andrespective hydrocarbon-carrying zones.

The valve system according to the invention is characterised in that thevalve housing comprises two separated casings in the form of an innercasing arranged inside an outer casing, where the inner casing can bemoved freely with regard to the outer casing, as the inner casingcomprises one or more ball seats, the one axially upstream of the otherand which is activated to hold back a ball, successively in that theinner casing can be moved axially through the outer casing.

Preferred embodiments of the valve system are as given in the dependentclaims 8-24.

In particular, the valve system is applied where it is inserted in aproduction string, to open a formation for production of hydrocarbonswhere, between each unit 1 of the valve system, a gasket is arrangedthat closes the axial fluid flow in the well (outside the productionstring), as the valve set is set up for successive opening of parts ofthe formation for production by the pumping-in of fluid via the valvesystem and which cracks the rock matter in the formation so that itstarts to produce hydrocarbons that then can flow into the well and upthrough the production pipe.

DESCRIPTION OF THE INVENTION

The present invention provides a solution to the problem of diameterrestrictions in oil and gas wells as a consequence of ball activatedvalves, where the seats for the balls normally form a restriction, inthat several valves in series can be opened with the same ball size at agiven point in time. This is carried out by (see FIG. 3) arranging anouter casing 2 inside the production pipe which covers the outletopening 14 in the production pipe when the outer casing 2 is in itsinitial position. Openings 29 that are also formed through the wall ofthe outer casing 2, and which shall later be aligned radially with theopenings 14, but which are not aligned in the initial position of thecasing 2, and are thereby closed for the fluid flow.

A new inner casing 3 that is comprised of several ball seats (see theperspective FIG. 13) of the same diameter is placed inside the outercasing 2. The uppermost ball seats in the inner casing 3 of the valveare not activated when the system is driven into the well, and will havea sufficiently large diameter for the first ball to pass freely, butwill stop in the bottom seat 4 a that is defined inside the outer casing2 since the constriction of the casing 2 forces the seat in the innercasing 3 radially inwards and hinders the ball from passing.

Thus, the first, for example, the bottom ball seat, is activated (i.e.that the seat is forced in and the ball 5 cannot pass) and thus set upto receive the first ball. When the first ball 5 lands in this activatedseat, it will, as a consequence of the fluid pressure, displace theinner casing 3 one step downwards so that the next ball seat, in theinner casing that is above the first ball, is activated as the seatenters into the outer casing 2 that has a diameter that is smaller andcompresses the seat so that it becomes activated. As the next ball seatbecomes activated the first ball is released in that this ball seatcomes axially out of the outer casing 2 and down in a larger diameter sothat the seat is no longer activated as the increased diameter permitsthe seat to expand and release the ball.

The outer casing which seals the passage out to the formation is held inplace by the friction or a form of locking device such as split rings,doggers or split fingers in a groove, as this locking device is releasedby the inner casing when it comes to its last position. Up to this, theinner casing is free to move axially through the outer casing. Thisprevents a complete opening occurring too early and alignment of theradially directed channels 14 and 29, respectively, in the valve. It isnot before the last seat in the inner casing 3 comes down to and movesdownward in the outer casing 2 that this is displaced and such that thenall openings 14-29-50 are aligned from the outermost to the innermost inthe assembly.

Then the first ball continues down the well pipe to the next valve wherethe same operation is repeated. Only when the correct number of ballshas passed and the last seat in the valve is active, i.e. has come intothe outer casing, will this open with a simultaneous downwarddisplacement and thereby both the openings 14 and 29 will be aligned. Asmaller fraction of liquid will also flow out through the slits 190 thatare formed between each finger 192, i.e. before the openings 50 arealigned with 14 and 29. It is only when the three openings 50, 14, 29align that one gets a full out/inflow of liquid through the channels 14and 29. Thus, an efficient counting mechanism is provided where theuppermost zone has, for example, ten ball seats where the first nine areused as a counting function in that the seat 1 activates the seat 2 whenthe ball 1 passes, seat 3 when ball 2 passes, etc. Then, when seat 10 isactivated the valve will be fully open (all openings 50-29-14 arealigned) when the ball 10 is let down into the well. Through this onecan provide a system where the bottom valve has one seat that opens whenball 1 is let down, the zone can then be cracked by the pumping of ahydraulic pressure.

For example, as can be seen in FIG. 4, the first ball has gone throughall the preceding sets of inner casings and is placed in the lowestthree. This has then led to that all inner casings 3 in each set aremoved down one step so that the outer casing 2 now surrounds andactivates the next lowest inner casing in each set.

When ball number 2 is let down it will land on the now active seat 2 inthe valve 2 from the bottom and up and open this, at the same time theball will now be held in place by the seat in valve 2 and be preventedfrom continuing down the well. Ball 2 seals now for flow past the balland zone 2 which is open above the ball seat can be cracked. This can becarried out without any of the above-lying zones being open and withoutany liquid flowing down to the zone 1 lying below.

Meant by ball is any object that is dropped down into the well, and itcan be a ball or a pellet of different, optionally varying materials,alternatively it can be an arrow that is especially designed for thepurpose or another type of object that can be pumped down in the wellwith the help of a liquid pressure.

The present invention also provides a solution to the problem ofresetting the valves to their initial position in a secure way so thatthey can be used for subsequent maintenance cracking jobs. This iscarried out in that at each end of the inner casing 1 that contains theseats a standardise profile for such operations that one can connect upis arranged. Such connecting up can be made in many ways but a commonmethod will be the use of coiled pipes. One can then either force allvalves open by driving in coiled pipes or one can force them to close.

This can be carried out in that one hooks on to the profile, either atthe bottom or at the top of the inner cylinder, and pulls or pushes thisto its final stop where the coupling is released. When the casing ispulled back to its initial position, the outer casing will be pulledalong up to the closed position. Similarly, the outer casing will followto the lower position if the resetting tool that fits in the profile ispressed down and thereby the inner casing that brings with it the outercasing to an open position.

It is implied that one can also use other standard profiles for suchresetting tools, and that it may be sufficient with one profile at oneend of the tool. It is also important to note here that the system isnot dependent on shear pins that are considered to be a one-time useonly solution. The system can, of course, be made with shear pins as areplacement for the preferred solution with split rings, but then onewill get a one-time use only system which is not the preferred solution,but which can be acceptable in some cases.

The present invention also solves the problem of pumping acement/concrete mixture past the valves as all the hollow spaces andsurfaces in the valve are filled/covered with an appropriatelubricant/grease that contains a sugar level high enough to preventhardening of the cement that is pumped past the valve. The sugar mixedwith the lubricant will hinder the cement from hardening in the areawhere the lubricant is, but will not prevent hardening of thecement/concrete that passes the lubricant. The present invention solvesat least one of the given problems.

The present invention provides a device according to the characteristicpart of the subsequent independent claims. Alternative and advantageousembodiments are given in the dependent claims.

DESCRIPTION OF THE FIGURES

A detailed, non-limiting description of possible embodiments of theinvention is given in the following, with reference to the enclosedfigures, where:

FIG. 1a shows a borehole 100 for a well that runs down through anoil/gas-carrying formation 102 and where a production string 104 runsdown in the well. It can be seen that the well runs vertically at first,thereafter to be turned in the horizontal direction. The figure shows anexample, where nine valve units 1 are installed in the well so that itis possible to pump fluid in sections into the formation 100 to make itready for production of oil/gas.

FIG. 1b shows an enlarged section of the horizontal part of the well andshows that gaskets 10 are placed around the pipe 104 between each valveunit 1 so that it is possible to isolate the sections from which it willbe sprayed out to crack open the formations. In this case, three suchzones are set up and three valve units are arranged in accordance withthe invention.

FIG. 2 shows a model of a well with several valves 1 a, 1 b and 1 cinstalled.

FIG. 2 shows a section of a preferred embodiment of a valve device 1 a,1 b and 1 c according to the present invention with a varying number ofball seats. The valve device 1 a has one seat 4 a, the valve device 1 bhas two seats 4 a and 4 b, the valve device 1 c has three seats 4 a, 4b, 4 c, as all three valve systems comprise an outer casing 2 thatsurrounds an inner casing 3. The valve 1 a is shown after the first ball5 has been dropped down in the well pipe and shows that the valve device1 a is on its way to be opened with the ball 5 placed on the seat 4 a.

FIG. 3 shows section details of valve 1 a from FIG. 2 with a first ball5 lying on the seat 4 a. Here, the following details are also shown: Anouter casing 2, a first casing 19 which, together with several units,will constitute an inner casing 3, a split ring 6, split rings 8,locking groove for split rings 11 and 12, gaskets 17 and 18, an openingchannel 14 in the wall of the valve 1 a, an opening channel 29 throughthe wall of the outer casing 2 and also the reset uppermost profile 20.The openings around the circumference of the inner casing 3 are shown by50.

FIG. 4 shows, in section, details of FIG. 2 after two balls have beendropped down in the well. Shown here is that zone number 2, marked bythe number 23 in the well 15, is ready for cracking by the pumping in offluid under pressure, as the ball 5 b (number two) lies on the seat 4 bin the valve 1 b, and the outer casing 2 is moved axially to an openposition from the inside to the outside of valve 1 b for flow throughthe channels 29/14, first through the slits 190 between each finger 192(FIG. 13) in the inner casing and thereafter through the openings 50 andfurther out through 29 and 14. We can also see that the well 15 isdivided into zones by the gaskets 21.

Zone 22 is cracked completely with cracks 25 with the help of fluidpressure. We also see that the ball 1 (5 a) lies on the seat in thevalve 1 a.

FIG. 5 shows section details of ball number two 5 b on seat 4 b in anembodiment, where the ball 5 b is held back in valve 1 b after the outercasing 2 is displaced so that the channels/openings 29/14 are alignedand the liquid can flow out outside the pipe.

FIG. 6 shows a section of valve 1 c with the third ball 5 c on the seat4 c that is actively displaced to this position by ball number to 5 b(see FIG. 5) that has previously gone past. Ball 5 c is now ready toopen the channel 29/14 in that it displaces the outer casing 2 axially(downwards). We can see a (schematic) threaded connection 16 at each endof the valve unit 1 c for coupling. Such connections can be found on allthe valves 1 for the purpose of fastening them to the production pipe26.

FIG. 7 shows a section of the valve unit 1 c where the inner casing 3and the outer casing 2 are mutually moved to an open position by settingup a fluid pressure above the ball 5 c. The ball is stuck as aconsequence of the fingers 4 a (194 in FIG. 13) being forced inwards bythe restriction that is formed by the outer casing 2, and all thechannels 50, 29 and 14 are aligned for through-flow of fluid. Thus, itis the last seat construction in the casing 1 that pushes the outercasing 2 along axially (downwards) so that the channels are aligned.

FIG. 8 shows a section of the valve unit 1 c when the first ball 5 apasses through this and lands on the seat 4 a. The arrows 27 show thedirection the ball moves from the top to the bottom. The number 16 showsthe threaded connection in the valve construction 1 c for securing (asan insert) to the production pipe 26.

FIG. 9 shows a longitudinal section of valve 1 c with ball number to—5 bon the seat 4 b.

FIG. 10 shows a section of valve 1 c with ball number three—5 c—on theseat 4 c.

FIG. 11 shows a section of valve 1 c with ball number three—5 c—on theseat now in an open position and channel 14 open and aligned withchannel 29 and 50, respectively, and also the restriction 9 for thesplit ring 6. The ball 5 c is held back in the restricted channel andfluid can be pumped out through the channels 50, 29, 14.

FIG. 12 shows a longitudinal section of valve 1 c that allows the ballnumber three 5 c through after opening of the valve.

FIG. 13 shows a 3D isometric perspective drawing of an assembled innercasing 3 that in this case encompasses three ball seat sections 19 a+19a+19 b, and also upper and lower sections 20 and 21, respectively, forthe coupling together.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The bottom of the two similar seat sections 19 a has a ball seat 4, i.e.as the first (lowest) unit. Number 4 b shown is the second seat in therow and the third unit is number 4 c, etc. The uppermost unit 4 c/ 19 bin this example has openings 50 in the wall around the whole of the pipecircumference and these are set up to align/correspond with the channel14 in the valve pipe 1 and the holes 29 in the outer casing 2 to offer afull and free opening in the open position for the pumping out ofliquid/fluid. The number 28 shows parts of the casing unit that are notsplit longitudinally so that several casing sections 19, together withend profiles 20, can be screwed together to form the inner casing 3.

In more detail, FIG. 13 shows an example of a multi-divided inner casing3 comprising lower and upper coupling parts 20 between which a number ofball seat sections 19 a and an upper section 19 b are inserted, forexample, by screw connections. Each of the sections 19 comprises a pipeend where, cut out in the ring-formed wall, is a number of axiallyformed U-shaped slits 190 which each define a flap—finger—4/192 that canbe bent outwards or inwards. At the bottom, each flap comprises athickening of the wall, a protrusion or a bead 194 that normally extendsoutside the outer side of the casing 3. Two such separated sections 19 aare shown in FIG. 13, plus a third section 19 b which, in addition toflaps 192, comprises a number of through-running holes/cut outs 50through the wall of the casing 19 b around its circumference. In aring-formed recess around the outer circumference at the upper part ofthe casing 3, a split ring is placed set up to be compressed in that ithits a restriction 9 (FIG. 11) in the inner side of the valve 1 when itis being pushed down.

The casing 19 is fitted inside the inserted valve casing 1, where thelowest section then lies mounted inside the surrounding outer casing 2.During said pushing down, the casing 3 is released for further axialtravel, independent of the casing 2. This release preferably takes placeafter the casing 2 is moved to an open position in the valve casing 1.

When the casing 3 is moved inside the outer casing 2 the radial,inwardly facing restrictions in the casing 2 will press against each ofthe beads 194 so that the flaps 192 are pressed radially inwards andthereby form a stopper seat for the balls/pellets 5 that are movedaxially inside the casing 3.

Furthermore, when the outer casing 2 is pushed downwards and theopenings 29 and 14 are aligned and form a radial flow channel,fluid/liquid can flow out through the slits.

In the preferred version the invention solves the problem of differentball sizes and the reduction of the diameter of the production pipe inthat all ball seats have the same diameter and, at the same time, can beactivated in a wanted sequence, typically from the bottom upwards.

In the present invention the object/pellet/ball 5 that is dropped or ispumped down the well will freely be able to move past all the seats in avalve 1 except those that are in an engagement with the outer casing 2that forms a restriction which forces the fingers 4 inwards and therebyprevents the ball 5 from continuing downwards. When the first activatingobject (ball) 5 is dropped down in the well, it will hit the lowest seatin the inner casing 3 that is in active position through the restrictionthat is set up by the narrower, inner opening of the outer casing 2.

Then when one drops a first ball or another activation object 5 down inthe well, in a valve with three seats, it will first hit the seat 4 cuppermost in the upper valve 1 c. The seat 4 c is now not activated(squeezed together) by the outer casing 2 and will let the ball 5through and go past. The same is the case for the subsequent seat 4 b inthis first valve 1 c (see FIG. 8). The ball rushes past the seats 4 cand 4 b till it hits the lowest seat 4 a which is now in an activeengagement (squeezed together by) with the outer casing 2 and throughthis is activated. When the ball hits the activated seat 4 a which isactivated in the outer casing 2, it will pull the inner casing 3downwards because of the pressure from above.

When the activated seat 4 a and the ball 5 on the seat have moved to theend on the outer casing 2, the ball 5 will be released again (therestriction ends), as the seat 4 a on which it lies is no longeractive—the fingers are forced outwards—when it comes out of the outercasing 2. At the same time, the axial movement of the casing 3 caused bythe first passing ball 5 will activate the seat 4 b which has now goneinto an engagement in the outer casing 2.

When ball 5 number two is released it will again move the inner casing 3axially downwards and release the ball 5 so that it can continue itstravel down the well to the below-lying zone. The valve 1 c in thepreferred embodiment has now counted two balls 5 without beingactivated/opened (without the channels 29, 14 being aligned). Then whenthe ball 5 number three is dropped into the well it will land on the nowactivated seat 4 c in the valve 1 c and again move the inner casing 3axially downwards because of the fluid pressure that builds up behindthe ball 5.

During the last move, the inner casing 3 hits a split ring 6 fitted onthe casing 3 (see, for example, FIG. 3) at the top of the outer casing 2and the pressure builds up behind the ball 5 such that the frictionacting on the outer casing 2 by the split rings 8 is overcome, the splitrings 8 lie in the grooves 11 and 12. When the friction generated by thesplit rings 8 is overcome, the outer casing 2 and the inner casing 3move together axially/downward with the help of the pressure that buildsup behind the ball 5 that lies on the seat 4 c. The axial movement ofthe outer casing 2 ensures that the channels 29 and 14 are aligned andopen for fluid connection out through the valve 1 c so that pressurecommunication with the well 15 lying outside is achieved through the nowopen channels 29/14. The now open channels 14 were previously closedwith the help of the gaskets 17 and 18 and also the outer casing 2.

In a preferred embodiment the split ring 6 is compressed in that it hitsa restriction 9 (FIG. 11) in the inside of the valve 1. This will againrelease the casing 3 for further axial travel, independent of casing 2.This release preferably takes place after the casing 2 has moved to anopen position in the valve 1.

When the casing 3 is released for further travel downward, it willrelease the ball 5 again to be able to operate one or more valvesfurther down the well, preferably with the same number of seats 4. Whenthe ball then hits the last valve 1 in the well with the same number ofseats 4, it will now be held back again either in that the restriction 9is removed and through this the compressing function this has on thesplit ring 6, or in that, for example, another physical form for the endstopper is inserted that prevents the split ring 6 from beingcompressed. Both these solution will hinder the last valve 1 and let theball 5 drop further down the well if they are placed correctly.

A third solution is that the inner casing 3 gets a separate end stopperthat prevents it from wandering so far axially that it brings the seatout of the outer casing 2. This can be in the form of a simple endstopper that cannot be compressed, but only pulls along the outer casingopen.

This will also leave the last valve in this zone open with the ball onthe seat which will thereby make up a seal so that it will be possibleto pressurise the well above the ball.

Between the ball 5 and the seat 4 there will always be some leakage, butthis is marginal in comparison to the leakage if the ball had not beenon the seat and has been shown to be of no significance. The point isnot to provide any 100% leakproof connection between ball 5 and seat 4but to set up a sufficiently large flow restriction which makes itpossible to build up fluid pressure above the ball 5.

It is implied that ball 5 number one (5 a) opened the bottom valve 1 aand that the subsequent next ball 5 opened the second bottom valve 1 b.

It is also implied that the valves 1 a, 1 b and 1 c could have anynumber of ball seats such as 4 a, 4 b and 4 c to become activated aftera correct number of balls has been dropped down into the well.Typically, there could be up to twenty zones in a well and then theuppermost valve 1 could readily have twenty such ball seats 4 to be ableto let nineteen balls 5 past before activation.

Another preferred embodiment is to use five different ball sizes to geta maximum of five seats 4 in each valve. This can be made due toproduction considerations. Then, one would be able to get twenty zonesin a well with relatively small restrictions compared with using twentydifferent ball sizes.

In a preferred embodiment the ball seats are formed through a partialsplit of a casing 19. A number of casings 19 is put together to thecasing 3 and the number of sections decides how many seats there are inthe valve and through this how many balls 5 that can pass beforeactivation. The use of such split casings is a well-known solution togenerate a radial, diametrical movement on a casing. Other known methodsfor this can also be used such as lugs that are activated when the innercasing 3 glides into the outer casing 2 or a split ring such as ring 6.Or other forms for embodiments where the seats in the casing 3 will beinactive when they are not compressed inside the casing 2.

Another preferred embodiment is that the seats 4, before entering intothe casing 2, are in an activated state but have no radial support fromthe outer casing 3 lying outside or from the body of the valve 1 itselfso that they can expand freely and let the ball 5 past. When the seats 4then move inside the casing 2, this will make up the radial support forthe seats 4 and through this activate these so that the ball willpush/move the casing 3 axially to the point where the inner casing 3with the ball seats 4 comes out again of the outer casing 2. In this wayit will be possible to achieve an identical function of the inventionwithout compressing the seats when they enter the casing 2 lyingoutside. It must also be understood that for such a solution,alternatives to seat 4 that are made up by the split fingers in thecasing 19 that together form the inner casing 3, could possibly be used,such as split rings, dogger pins or other solutions where the outercasing 2 constitutes a radial support for the seats 4 and through thisprevents the ball 5 from passing.

According to a preferred embodiment of the invention, there will be mostball seats 4 a, 4 b, 4 c etc., in the upper valve and least on thebottom valve. For example, the upper valve can have ten seats and thelower one seat, the second bottom two, etc. Then one will be able to leta ball 5 go through all the valves and land on the bottom valve 1 a.When it lands on the bottom valve 1 a, it will immediately move axiallyas it rests on a split ring 6 that constitutes the end stopper for theinner casing 3 relative to the outer casing 2.

According to a preferred embodiment of the invention, all internalhollow spaces are filled with a viscous lubricant, such as a petroleumbased grease, a heavy paraffin wax or a natural grease that containssufficient amounts of sugar which will prevent the cement that maypenetrate into the hollow spaces from starting to harden. This lubricantcan also include beeswax, or pure honey that will also prevent that thecement (the concrete) is hardened, at the same time as it provides alubricating effect. The point is that this lubrication contains a typeof chemicals, such as sugars, or something else that prevents hardeningof the cement. The hardening of the cement can also be stopped by mixinginto other known chemicals in this area; such chemicals are regarded tobe incorporated into the invention and are not described further herein.

In its simplest form the valve can be comprised of a casing 2 fittedinside a production pipe, this casing is set up to seal for outflow orinflow through openings in the valve pipe 1 in its first position. Inits second position the casing 2 permits free flow of liquid or gas,either from the valve pipe 1 out into the formation or from theformation and into the valve pipe. Inside this casing 2 an inner casing3 is placed as described, that has one or more ball seats that have thesame diameter in the preferred embodiment. This inner casing is free tomove axially in the outer casing between two end stoppers that willprevent the inner casing 3 from sliding out of the outer casing 2.

One can also imagine solutions where the ball seats in the inner casing3 have several diameters to further increase the flexibility of thevalve.

In cases where one of the casings is stuck or one shall return the valveto its initial position, the inner casing can also have built-inprofiles for well tools so that it can be displaced axially also withthe use of typical coiled pipes or wireline tools or other wellintervention tools that are used.

The main aim of the counting mechanism is to open the valve at thecorrect point in time, but it can, of course, also be used to activateother well equipment via the same time-providing or counting function.The following examples can be mentioned, amongst others: activation ofwell perforation cannons, activation of other types of well inflowvalves, injection valve for chemicals, gas-lift valves and so-calledsliding sleeves.

The valve casing 1 can preferably be produced in any material suitablefor installation in a well, and typical examples can be mentioned,amongst others, some used steel types such as ASI 4140, 420 mod 13% Cr,super duplex or high grade steel such as Inconel 718 without and thematerial types of valve 1 to these. One can also imagine that ceramicmaterials and other composite materials can be used.

The material types for the other parts of the valve can typically be thesame as for valve 1, but for the inner casing one will preferably choosea flexible material that can also be a steel spring that makes movementspossible for the seats in the casing 3.

While the invention is described with reference to a preferredembodiment, it shall be understood that a number of modifications can becarried out without going beyond the extent of the enclosed claims.

1. Method for the operation of a valve system for a production pipe(104) in a well (101) through a hydrocarbon containing formation withone or more valves (1 a, 1 b, 1 c) that comprise one or more seats thatare activated selectively by the use of a ball (5) of the same size,where the ball is set up to land on one or more ball seats (4 a,b,c, . .. ) internally in the valve, where the seats (4 a,b,c.) can be activatedfor the landing of a ball (5 a) either before driving into a well or inthe passing of a previously released ball or other suitable object (5)of an adjusted diameter or shape, characterised in that each appliedvalve (1 a, 1 b, 1 c) comprises two separated casings (2 and 3,respectively) in the form of an inner casing (3) arranged inside anouter casing (2), where the inner casing (3) can be freely moved axiallywith regard to the outer casing (2) as the inner casing (3) comprisesone or more ball seats (4), the one axially above the other, and whichare activated to retain a ball (5), successively in that the innercasing (3) is moved axially through the outer casing (2).
 2. Methodaccording to claim 1, characterised in that the inner casing (3) dragswith it the outer casing (2) to an open position when the ball (5) landson the last seat (4 a) in the row in the inner casing (3) so that itopens for fluid connection between the inside of the pipe (104) and theformation (100) through aligned openings (50, 29, 14) in the innercasing (3), the outer casing (2) and the valve (1 a), respectively. 3.Method according to claim 2, characterised in that the last seat (4 c,FIG. 13) in the inner casing (3) forms a restriction so that the ball(5) is not set free when it lands on this last seat (4 a).
 4. Methodaccording to claim 2, characterised in that the last seat (4 c) in aninner casing (3) sets the ball (5) free after an opening of the outercasing (2) that makes up the valve, for example, so that several valves(1) are installed in the same using zone where the bottom valve (1) willthen hold back the ball (5) and through this sets up several openingsfor fluid flow out to and in from the same zone in the formation (100).5. Method according to claim 1, characterised in that the well (100) isdivided into zones in that the pipe (104), between each set of valves (1a, 1 b, 1 c), comprises gaskets (110) that form a seal between theformation and the pipe (104).
 6. Method according to claim 1,characterised in that the bottom valve set (1 a) in the production pipe(104) comprises one single casing with a ball seat (4 a) and alsoopenings (50) uppermost around the pipe circumference to set up saidflow of fluid to a first zone, a second valve set (1 b) comprising twocasings with respective ball seats (4 a, 4 b) where the uppermost casingcomprises openings (50) uppermost around the pipe circumference to setup said fluid flow to a second hydrocarbon-carrying zone, as eachfurther valve set (1) in the row upwards comprises one casing more thanan underlying casing, as each uppermost casing comprises said openings(50) uppermost around the pipe circumference to set up said fluid flowbetween the pipe and the respective hydrocarbon-carrying zones.
 7. Valvesystem for application in a production pipe (104) in a well (101)through a hydrocarbon-carrying formation and which can be activatedselectively by the use of pellets or balls of a single size, where theball is set up to land on one or more ball seats inside the valve, wherethe seats (4) can be activated for landing of a ball (5) either beforedriving into a well or in the passing of a previously dropped ball orother adapted object (5) with an adjusted diameter or form,characterised in that the valve housing (1) comprises two separatedcasings (2 and 3, respectively) in the form of an inner casing (3)arranged inside an outer casing (2), where the inner casing (3) can bemoved freely with regard to the outer casing (2), as the inner casing(3) comprises one or more ball seats (4), the one axially above theother, and that are activated by retaining a ball (5), successively inthat the inner casing (3) can be moved axially through the outer casing(2).
 8. Valve system according to claim 7, characterised in that thelast seat (4 c, FIG. 13) of the inner casing (3) forms a restriction sothat the ball (5) is not released when it lands in this last seat (4 a).9. Valve system according to claim 7, characterised in that the lastseat (4 c) in the inner casing (3) can release the ball (5) after theopening of the outer casing (2) that makes up the valve, for example,such that several valves (1) are installed in the same using zone wherethe bottom valve (1) will then hold back the ball (5) and through thismake possible several openings for the flow of fluid out to and in fromthe same zone.
 10. Valve system according to claim 9, characterised inthat the first ball seats (4) in the inner casing (3) lets the ball (5)pass the valve (1) and axially downwards to a next valve (1) in a rowwhen the inner casing (3) in its activated (constricted) seat (4) comesout of engagement with the outer casing (2) and into the now increasedinternal diameter (ID) of the valve (1).
 11. Valve system according toclaim 10, characterised in that the first ball seats (4) displace/move,with the help of the pressure behind an activation object, the innercasing (3) axially down a position for each activation object/ball (5)which, by fluid pressure from above, is pumped down into the well,thereby to activate a last seat (4 c—FIG. 13) to finally open the valve(1) by an axial displacement of the outer casing (2) in parallel withthe inner casing (3).
 12. Valve system according to claim 11,characterised in that the inner casing (3) comprises one or more endpieces/end profiles (20) for connection of a resetting tool.
 13. Valvesystem according to claim 12, characterised in that the outer casing (2)in the valve (1) is physically locked to the valve via at least onesplit ring (8) up to the inner casing (3) being moved to a positionwhere a last seat (4 c—FIG. 13) is activated and is then released foropening in that the friction in the, at least, one split ring (8) isovercome by the pressure that builds up behind the ball (5), and throughthis overcomes the friction that is made up by the locking.
 14. Valvesystem according to claim 7, characterised in that the outer casing (2)can be prevented from moving by the use of locking bodies, for example,a shear ring, shear pin and split fingers, said locking body immobilisesthe outer casing in a position for fluid flow by said movement of theinner casing (3).
 15. Valve system according to claim 14, characterisedin that the locking body of the outer casing (2) is held locked via apressure supplied by the inner casing (3), in that the pressure from theadapted inner casing (3) influences one or more pegs that are forcedthrough the outer casing (2) by the inner casing (3) and out into a cutgroove in the wall of the valve, when the inner casing (3) reaches itsactivation position, this has a smaller diameter in an area that makesit possible for the pegs to collapse inwards and release the outercasing (2) for movement so that the openings (14, 29) are aligned forfluid flow.
 16. Valve system according to claim 7, characterised in thatthe inner casing (3) comprises ball seats (4) for the placing balls ofdifferent diameters to further increase the flexibility of the system.17. Valve system according to claim 7, characterised in that the outercasing (2) is held in place by, for example, a split casing that exertsa friction out against the outer wall of the valve.
 18. Valve systemaccording to claim 7, characterised in that all inner hollow spaces andall exposed surfaces are filled with a lubricant that contains achemical that prevents hardening of cement, such as, for example, sugar.19. Valve system according to claim 7, characterised in that the outercasing is fitted with internal cut that will make expansion of the ballseats (4) possible to release the ball before the ball seat is out ofthe outer casing (2). 20.-21 (canceled)
 22. Valve system according toclaim 7, characterised in that the inner casing (3) or the outer casing(2) is with, for example, one or more split rings for increased frictioninner casing (3) or outer casing (2), or by other known constructionsfor increased friction, such as a coarser surface on the material,another material than on the other parts, a covering of anothermaterial, grooves in the material, C-clip rings, shear rings or shearpins for the purpose of preventing unintended movement of the outercasing (2).
 23. Valve system according to claim 7, characterised in thatthe valve (1) comprises ball seats that are set up to first open thevalve and then to close it if further balls (5) are let down into thepipe/well (1/3).
 24. Valve system according to claim 7, characterised inthat a bottom valve set (1 a) in the production pipe (104) comprises asingle casing with one ball seat (4 a) and also openings (50) uppermostaround the pipe circumference to set up said fluid flow to a first zone,a second valve set (1 b) comprises two casings with respective ballseats (4 a, 4 b) where the top casing comprises openings (50) uppermostaround the pipe circumference to set up said fluid flow to a secondhydrocarbon-carrying zone, as each further valve set (1) in the rowupwards comprises one casing more than in an underlying valve set, aseach uppermost casing comprises said openings (50) uppermost around thepipe circumference to set up said fluid flow between the pipe andrespective hydrocarbon-carrying zones.